BIOL111 Lecture 3

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BIOL111 Lecture 3
2012-09-30 21:13:17
BIOL111 Lecture

BIOL111 Lecture 3
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  1. In which geological era did prokaryotes first appear?
  2. How can we define diversity in life or biodiversity?
    • Degree of differences in:
    • genetic variation
    • species composition
    • interactions within and between ecosystems
  3. What is species diversity?
    commonly reserved for indices that measure both the number of species in a habitat as well as their relative abundances
  4. How many species have already been named?
    about 1.5 million
  5. How many new species are named each year?
    • about 13,000
    • but about 3,000 are synonyms (duplicated species)
  6. What is tree fogging?
    • technique designed by Terry Erwin in 1983
    • fog one tree, killed all the species in it, then classify them all
    • found 160 beetle species unique to that tree species, about 50,000 tropical tree species, beetles are about 2/5 of all insects which are about 1/2 of all species
  7. What is the current estimate for extant eukaryotic species?
    • 3-100 million
    • sir robert may's guess is 7 million
  8. what percentage of all species are extinct?
  9. what is the current estimate for how many bacteria and archaea there are?
    about 10,000 bacteria species have been identified but could easily be millions or 100s of millions
  10. What are the 2 main factors that control diversity?
    • area
    • climate
  11. How does area affect diversity?
    In general doubling area increases number of species by 10-25%
  12. How does climate affect diversity?
    • warm, wet areas have more species
    • but we don't know why exactly
  13. Mammals represent ___% of diversity of eukaryotic organisms
  14. Beetles represent ___% of diversity of eukaryotic organisms
  15. What is genetic diversity?
    measure of genetic distance (evolutionary separation)
  16. What is functional diversity?
    Differences in shape, size, and generally ways of making a living (types of food, places lived, etc)
  17. Which group shows the greatest genetic diversity?
  18. Which group shows the greatest functional diversity?
  19. Where is diversity greatest geographically?
    near the equator on large landmasses with good climates
  20. Which group of organisms are the Earth's oldest organisms?
    Prokaryotes (2 major groups, bacteria and archaea)
  21. Which domains have a membrane enclosed nucleus?
  22. Which domains have membrane enclosed organelles?
  23. Which domains have peptidoglycan in the cell wall?
  24. What are the defining characteristics of Archaea?
    • absence of peptidoglycan in cell wall
    • distinctive lipids present in their cell membranes (not found in eukaryotes or bacteria)
    • many archaea also have lipid monolayer
  25. How does the DNA of archaea and bacteria differ from ours? 
    • Have single circular chromosome and plasmids
    • Located in the nucleoid region
    • chromosome not highly coiled
  26. What are plasmids?
    Extra-chromosomal DNA; small rings; easily exchanged during sex
  27. Bactera do not have ________ organelles
  28. What is the use of the cell membrane in bacteria?
    highly folded, site of ATP synthesis & photosynthesis
  29. How do bacterial ribosomes differ from eukaryotes ones?
    Lack of nucleus, allow simultaneous transcription and translation = fast growth and reproduction
  30. What are the 3 morphological differences in bacteria?
    • spheres = cocci
    • rods = bacilli
    • helical = spirili
  31. How can we determine varieties in cell wall structure in bacteria?
    gram staining
  32. What does it mean if a bacterium is gram positive?
    Thick layer of peptidoglycan in the cell wall structure
  33. What does it mean if a bacterium is gram negative?
    Thin layer of peptidoglycan in the cell wall structure between 2 membrane layers
  34. typically antibiotics are ineffective against gram _____ bacteria
  35. How do bacteria reproduce?
    • rapid, short generation times
    • asexual reproduction - "binary fission" - literally divide in half
  36. How do bacteria exchange genetic material?
    • 3 main methods to obtain new genetic material
    • genes on plasmids are easily transferred 
    • in conjugation, replicated genes are transferred through hollow tubes called sex pili 
  37. How do bacteria maintain homeostasis?
    • respond to harsh environmental conditions
    • move toward or away from chemicals
  38. what is an endospore?
    • something a bacterium forms for protection
    • protect bacteria from adverse conditions, helps keep it alive in harsh conditions and for a long time
  39. What is a biofilm?
    • bacteria form surface-coating communities called biofilms
    • form polysaccharide gel trapping debris and other cells
    • can be hundreds of cells thick
    • composed of single or many species
    • an example is plaque
  40. What is chemotaxis?
    The ability of bacteria to move towards or away from chemical signals
  41. How do bacteria perform chemotaxis?
    • Use flagella (different than eukaryotes - made from different protein, thinner, more numerous)
    • Also glide, roll, use gas floats inside cell
  42. How do bacteria transform energy?
    • despite their simplicity in cell structure, prokaryotes are extremely diverse in their metabolic abilities
    • variety due to diverse habitats and long evolutionary history
  43. What are photoautotrophic bacteria like?
    • Transform light energy into chemical energy = photosynthesis
    • absorb light energy with chlorophyll
    • use light energy to convert CO2 into glucose
    • produce O2 as a waste product
  44. What are aerobes?
    obligate aerobes must use oxygen for long-term metabolism
  45. what are anaerobes?
    • do not require oxygen for metabolism
    • make ATP using fermentation, not cellular respiration
  46. What are obligate anaerobes?
    oxygen is toxic to them
  47. What are facultative anaerobes?
    use oxygen if it's available
  48. What are aerotolerant anaerobes?
    can survive in oxygen environment but do not use oxygen
  49. Most prokaryotes and other organisms do what to get energy?
    • they are chemoheterotrophs
    • consume organic molecules for carbon and energy source
  50. What are some of the roles that heterotrophic prokaryotes can play in the biosphere?
    • decomposers
    • symbiosis with eukaryotes (like herbivores)
    • pathogens
  51. What do nitrogen fixing bacteria do?
    Why is this important?
    • convert atmospheric N to NH3
    • plants are dependent on nitrogen-fixation
    • crop rotation often involves planting legumes (N-fixing bacteria often live on roots of legumes)
  52. How is illness to host caused by pathogenic bacteria?
    Caused by toxins
  53. What are exotoxins?
    • secreted proteins, very toxic
    • example: botulism, tetanus
  54. What are endotoxins?
    • outer bacterial membrane, rarely fatal
    • example: salmonella and E. coli (food poisoning)
  55. How are bacteria classified?
    • Traditionally by shape and gram stain
    • Now based more on DNA sequencing